"If you throw up in an Uber, the surcharge can be substantial," he quipped. But the risk has rewards. He says it's a "market incentive to get drivers to agree to" Saturday night shifts.

Sasse emerged as one of Donald Trump's harshest critics before the election. After Trump defeated Democrat Hillary Clinton last week, Sasse congratulated Trump and said he and his family will pray that the billionaire businessman will lead "wisely and faithfully keep his oath to a Constitution of limited government."

But the senator, a former college president who was elected in 2014 with support from the tea party, also said he will do everything he can to hold Trump to promises he made during the campaign.